Trailer coupler



June 8, 1948. J. N. APGAR TRAILER COUPLER 3 Sheets-Sheet 1 Filed June 3, 1946 June 8, 1948. J, N, A'PGAR 2,442,914

* TRAILER COUPLER Filed June 5, 1946 3 Sheets-Sheet '2 il N i 1 m d June 8, 1948. J. N. APGAR TRAILER COUPLER 5 Sheets-Sheet 3 Filed June 5, 1946 f w ai W @V M. mw 1w .mv d w W .U O 3 M@ (6 u Patented June 8, 1948 2,442,914?, TRAILER COUPLER John N, Apgar, Boundlroolr, N. lJ. Application JvunefS, 1946, Serial No. 673,914;

Y 14 ciertos), (c1. retreats) This` invention relates to trailer couplers r fifth. Wheel .constructions such as Vemployed 'in trucking .equipment for. connecting. trailers .and semi-trailersrto tractor units..

Thiseapplicationl is4 a continuatonrurlr .-Qf, and'rsubstitute for, my` copending application Serial Numbert547,148, filed JulyA 29, 1944,. now abandoned.

The fth Wheelcouplings and auxiliary gear now in general use VarysOmeWhat as todetails but -theyare basically so `similar. in constlution and operation as to comprisea type that will be reierred to herein asrtheconventional fth Wheel coupling-1 of present .trucking practice. The main bearing-portion of this Lconventional coupling comprises a plate, Whichmay bea steel casting, thatvis supported on the tractor unit for rocking movement about an axis parallel to and above or-somevvhat in front of the rear axle of the. trac.- tor-funi-t. This rockingfrmountingis provided by a"v shaft, or axially alined shafts, that extend transversely across tlfieA tractor. unit and are mountedin'trunnions secured respectively to said bearing plate and to the tractor frame.. The forward half of the bearing plate is semifcirculan irrplan view, andthe rearhalf .is forked to p rovide afguide for the introduction of theking pin carried-'byafiat plate rigidly ,fastened to the underside of the vforward end `of thetrailer body. Aslatchor" clutch mechanism is attached tothe underside of the Amounting plate to close upon the;king` pin as itreaches the end of the, guide slotto complete the coupling of the tractortrailer combination. The two .platesand theking pin form the 'fth wheel connection thatpermits thetractor and trailer to assume diierentsangular-relations duringV travel along winding roads, and'in turning corners or parking. Independent movement of the tractorA and trailer to follow. ups andvdovvns of theroadris providedvbyf. the rockingmounting of the bearing plate of the tractor.

YThis type of lfth wheel coupling has notbeen entirely satisfactory inspite of its almost universalusein the truckingindustry. The rocking mounting offthe tractor ybearing plate aiordsa stable support for the semitrailerl vWhen the tractor` and trailer are alined longitudinally, since the axis ofl rocking movement is then Aparallel to the single axle atV the rear of thesemitrailer, but the. resistance. to. tilting decreases progressively as the. tractor unit moves outv of .longitudinal alinement with thetrailer. In turningf. sharp cornersor in. parking; maulllrs, lille resistance. to tilting, or, upset ci the.. trailerK Afalls tothat of: o, threev point.. support. as the. tract@` 2 moves to an angle of with respeot-to the trailer v'bjets' of` the present ention vare to pro vue. new. trader-ital@ Gemelli I Off eew' fifth Wheel couplings fortra'ctor-trali;

the invention are to provide'tacto binations and 'fthWheelcor'i's'tru'o'L Semewhich iifr flun'riveritional pr .that the. bearing plate oftlie tractor mounted on aturntable and the' copelfalti'hgil` offlletrailer unit caii'b latchedt'i'th bearing plate to retain the rozkinga'xi tractor tearing plate parallel totn'axie Arear of the trailerMu'ntl' Other bj'ectsK-a provide turntable assemblies fdritheion offcanventioual fifthuhl biip'liss i chaniallystable tractor'traile" "couplin' ther objects. are .te 'brqv'df 'tiatQ-tr sembues and. @Purline system frA tractorassemblies. in which increased stability 'in ation is obtainedbvdisplains therut o ap.- plication, of the trailenweight.laterallw .f the trac'tor'when roundin'ga curve, thediregtion of thfodispaoehieiitbeing towards the vinside ofthe cive'i "I'liese and other objects and advantages of the invention fvvfill" b e" apparent from' the ffollowing spe'ciflcation `vs'lhe'rr italien vvithftlie accompanying pling elements mounted on thetractorunit; v

vthe frame channels Fig. 3 is an exploded view, on a larger scale, of the fth wheel construction;

Fig. 4 is a central section as taken on the plane of line 4-4- of Fig. 2;

Fig. 5 is a plan view of the plate secured to the trailer unit;

Fig. 6 is a detail fragmentary View, in section, showing the mechanism for actuating the latches for connecting the bearing plates to each other;

Fig. '7 is a fragmentary side elevation illustrating another embodiment of the invention;

Fig. 8 is a schematic plan view of another coupling assembly embodying the invention, the tractor and trailer being shown in broken line in position rounding a curve;

Fig. 9 is a fragmentary plan view of the tractor section of the coupling unit; and

Fig. 10 is a central vertical section through the coupling unit and adjacent parts of the tractor and trailer.

In the drawings, the reference numeral I identifies a tractor unit of a short wheel base type to which a trailer unit 2 is releasably connected by a fth wheel coupling. The rear end of the trailer is spring-supported on wheels 3 in the usual manner, and the front end is provided with some form of landing gear, such as wheels 4 on telescoping legs 5, for supporting the trailer body when separated from the tractor unit I. The frame of the tractor, comprising side channesl 6 and cross braces 1, is supported on the rear axle 8 by the springs 9, and the axle is supported in turn by the wheels III. l

" The elements of the trailer couplings on the tractor unit include a main bearing plate II of the usual forked or yoke shape that is connected to a base or platform I2 by rubber mounted bearing pins I3 and trunnions I4, I5 on the plate II and base I2, respectively. An automatic or semiautomatic clutch handle I1, is mounted on the lower face of the plate II to engage the coupling pin I8 and latch the upper bearing plate I9 to the main bearing plate II. The pin I8 is welded to the plate I9, and the latter is rigidly fixed to the trailer 2 in conventional manner.

The elements so far described will be recognized as identical with or at least the structural equivalents of corresponding parts of the fifth wheel couplings now in general use in the trucking industry. The trunnions I5 of the conventional couplings have usually been secured directly to the frame of the tractor and, when a base or platform I2 has been used, it took the form of a casting or rough plate that was rigidly fixed to the tractor frame. In accordance with this in vention, the platform I2 is the top plate of a turntable which constitutes the true fth wheel of the trailer coupling. The turntable base cornprises a thin steel bearing plate 2u, usually of circular form, welded to a heavy supporting plate 2I which, in turn, is welded to a framework of cross channels 22 and longitudinal channels 23. A thick plate or bushing 24 is welded to the lower face of the plate 2l to increase the length of the bearing provided for the turntable pin 25 that is welded to the upper plate or table I2. The lower end of the pin 25 is circumferentially grooved to receive the clamp ring 25 which retains the turntable in assembled condition. The turntable base is rigidly securedto the tractor frame by U-bolts 26 that pass through openings in 22 and the supporting plate Keys or latches 21 are mounted on the ends of I6, together with its releasey leaf springs 28 secured to the lower face of the bearing plate II, the keys 21 extending through openings in the plate to enter tapered. slots 29 in the bearing plate I9 that is fixed to the trailer. Yokes 30 are welded to the ends of the springs 28 and a bent rod or crankshaft 3I extends through the yokes and is journalled on the plate I I to serve as a release member for the keys 21. A link 32 is pivotally connected to the arm 33 that is secured to the release shaft 3|, the outer end of the link being slidably supported in a bracket 34 that is welded to the plate II. The link has a pair of spaced holes 35 that aline with a hole 36 in the bracket when the link is in its end position corresponding to an adjustment of the keys 21 to projected or, alternatively, to retracted position. Actual practice has proved that the spring mounting of the keys 21 is sufficient to retain them in projected positions under normal driving and parking conditions but it is preferable to supplement the spring action by a mechanical lock when the coupling is not apt to be released or to come under observation for long periods of time for any reason, or when unusually rough driving conditions are to be encountered. This mechanical lock is supplied by inserting a pin or bolt 3B in the alined holes 35, 36 of the operating link 32 and the bracket 34.

It will be apparent that the latching of the bearing plates II, I9 to each other by the keys 21 results in a mounting of th'e bearing pins I3 in iixed position with respect to the trailer, i. ewith the axis of th'e pins I3 parallel to the axle of the wheels I0 of the trailer. The turntable structure provides the iifth wheel coupling wh'ich permits relative angular movement of the tractor and trailer units, and the lateral or sway stability of the trailer is not affected by the turning of the tractor with respect to the trailer. The tractor and trailer are coupled in the usual manner by backing the tractor to carry th'e forked plate I I under the plate I9 of the trailer, and the units are separated in conventional manner after actuating the clutch release lever I1 and the key release link 32.

^ Existing trailers with bearing plates not provided with key-receiving slots may of course be coupled to tractors having fifth wheel couplings as herein described as the trailer plate will merely ride upon and depress the keys 21, or the keys may be depressed and locked down by the release link 32. The turntable must be locked against operation with such a new tractor-conventional trailer combination, and this condition is readily attained by providing the plate I2 and plates 28, 2l with openings 31, 31 respectively in which a pin 38 may be inserted to lock the turntable with the axis of the rocking pins I3 parallel to the wheel axles ofthe'tractor unit. Trailers with coupling mechanism ofthe new type may be operated by tractors 'with the conventional `fifth wheel couplings as the slots 29 in the trailer bearing plates I9 will not interfere in any way with angular movement of the contacting bearing plates about the axisof the coupling pin I8.

The mechanical locking of the tractor 'and trailer bearing plates respectively may be effected by mechanism' correlated to the landing gear of the trailer unit. As illustrated inFig. '7, a latch keyor pin 39 on the trailer unit is carried by a bell-crank lever 40 th'at is urged in counterclockwise direction by a spring 4I to project` the pin through openings in the plates II', I9' and is rocked clockwiset'o prevent this coupling by a iiexiblel connection 42 to va reciprocating element 3 of the telescoping' legzfof Kthe trailer landing gear. The coupling devices; on theftractor are of the turntable supported type, as-previouslycdescribed,` andthe tractor. andrtrailerfunits:are-cone nectjed in' theconventionalf manner bytzbacking. the-tractor to-,carry the fo'rked'l'alatel l le beneath the'tr'ailer bearing pla-te' I9. The landing. gear isf then 'retracted` and the lifting 'of the4 member 4,3? slacks oir'the flexible connection 4.2;- to permit angular movement of lever lill.byfthespringM toycarry the latch: pin l 39.' intolthe openings oi the bearing plates.

As; withV the embodiment yof the invention illus# tra-ted in Figs. 1` to 6, tlietr'acto'r' andltrailer units with' coupling devices 'off thei Figsf'? vtype can be used interchangeably. with tractor-and `trailer units'v havingnfth wheel: couplings of conventionalrtype.

A marked increase'in stability is-cbtained'y by shiftingthe point ofV application oithe trailer weight to the-rear ofrthe turntableaxis. Ass-uming av uniform distribution of` the loadin `the trailer, about one-half of the trailer weight load is transmitted to the turntable through the shaft I3' land trunnions 14'; i5, and the resultant of these-forces. orv weights acts vertical-lyl through the midapoint` between the trunnions ifi',- I5- and, in the conventional fifth-wheel constructions such as here illustrated, the axis of the fth wheel king pin' I 8. passes through this mid-point. preferred-'embodiment of the invention which -is illustrated in: Figs. `8,-9'and 10, the shaft i3 and the king pin |8 :are located rearwardly of-the turntable king pin 25 by a short distance, and the point of application of the trailer weigh't thereby moves laterally of the trailer, see Fig. 8, when the tractor-trailer assembly enters a curve. This lateral displacement of the trailer weight. is towards the inside of the curve wheth'er the turn is towards the left, as illustrated, or towards the right, i. e. in the centrifugal forces which tendl to increse the-portion'. of` the trailer load th'atl is carried by the outside rear. wheels lll ofthe tractor.

The detailed construction of the coupling may conform to that of either of the previously described embodiments except, cf course, for rearward displacement of the axis of the shaft I3 (and of the fth' wheel king pin I8 which is vertically alined therewith) from the turntable king pin 25 by a short distance d, see Fig. 10. Except for this change, the coupling illustrated in Figs. 9 and 10 is substantially identical with that shown in Figs. 1 to 6 inclusive, and th'e several parts have been identified by the same reference numerals but will not be described in detail.

The full advantages of the invention are obtained only when both the tractor and the trailer units have the novel types of cooperating coupling members but the adaptability of tractor and trailer units with new coupling devices for use with' units having conventional coupling devices is an important feature of the invention.

It is to be understood that the invention is not limited to the particular constructions herein illustrated and described as various modifications that may occur to those familiar with the design of trucking equipment fall within the scope of my invention as set forth in the following claims.

Iclaim:

1. A mounting for the tractor section of a fth whee1 assembly, said mounting comprising a base to be secured to a tractor, a lower turntable plate rigidly secured to said base, an upper turntable plate to which said tractor section of the In theproper' sense to oppose thefth-wheel assembly maybe secured, 'a turntable pin welded-to Isaid upper fturntableiplate andpiv.: otally econnecting said: 'plates 'fo-r; angular-1 :moveiy ment, .saidvlowen turntable platefcomprising. a thin. '.steelc` pl'ate.- and. afsupporting -platetherefor weldedi tdsai'df base,` and a bushing Weldedto' .said supporting@ plate to. increase ,i the flengthi' of; the bearing for said turntable pin.

2, llli-mounting forithel traotor'section-:ofia fifth wheel. assembly, said; v.moun-tirigc comprisingw` a base to bei secured to -a1tractorg a lowerf turntable platel rigidly.: securedrtosaid bas'eg-an-Iupperi turni4 table f plate: to which said: tractor.- fsection.' oir-the nfthwheeliassem'bly may. besecured-,u'a turntable pin welded tos'aidupp'er turntable-plate andpiv-f otally connecting saidfxplatesfor: angular-mlov ment :and -a bushingiwelded-'td said; supporting' platefto.:l increase the; lengtliiifoitl'ieibearing1 for saidtfurntable pin;- .A

3. A conversion unit for use;with-fracon-vouv tionalsntth wheeLcoupl-ingot the) typegincluding an upper. lbearingl-plategand coupling-lpinfrigi'dly secured-tol a` trailer, Ia .lower bearing plate-ofiyoke shape forireceiving-.the coupling pin; and bearing me'ansi-rigidlysecined:to.a tractor supporting said lower bearing.- plate `for` rockinglmovementl-about a horizontalf' axis transverse (to -ther-"ax-is orf-the tractor;` saidiconversionunit adaptingtsaid lower bearing plate :fori rocking; movement about fan axis ,i transverse tothe ti-"ailer,l and comprising '-a lower` turntable plate to be rigidly secured tti-the tractor; an upper turntable plate upon -whichlthe bear-in'g-means'v of the conventional-nim wheel-iis to--'be secured, means. coupling saidf-turntable plates-for. angular movement; {wherebyl said bearing plates of. 'the Vcon'venltion'al'=i'lfth l wheel-focuplin'ggmay be. provided withimeans-latching--said bearing plates to each other with-theaxi's' of'sa-id bearing i rneansi transverse to fithe'- trailf'zlrf and means fon-locking said turntable plates to'-eaoh other with ther axis `of--thebearingfineans-transh verse to ther tractor, whereby Va 1 tractor providedwitha-conversiorr unit may be-employed-witlia trailer` not 1 equipped-1 with means for locking-the bearing plates to each other.

4. A conversion unit as recited in claim 3, wherein said latching means includes a key, and spring means securing said key to said lower bearing plate and normally projecting the key above the upper surface thereof to enter an opening in the upper bearing plate,

5. A conversion unit as recited in claim 3, wherein said turntable plates are pivotally interconnected by a pin secured to and depending from said upper turntable plate, and a bushing for said pin is secured to and depends from said lower turntable plate.

6. In a fth wheel trailer coupling for a tractor-trailer assembly, a bearing plate and coupling pin adapted to be rigidly secured to a trailer, a cooperating lower bearing plate having a slot therein for receiving said coupling pin, means supporting said lower bearing plate for rocking movement about a horizontal axis, means to be secured to a tractor unit for mounting said supporting means for angular movement about a vertical axis on the longitudinal center line of the tractor and in front of said horizontal axis of rocking movement, and means for latching said bearing plates to each other with the axis of rocking movement extending transversely of the longitudinal center line of the trailer.

7. In a trailer coupling for a tractor-trailer assembly, a turntable to be rigidly mounted on `a tractor, said turntable including a lower` iixed plate andan upper plate secured to said'lower plate for angular movement about aiverti'c'al axis, andmeans mounted .on the upper bearing plate for connectioneto a trailer to supportthe same for rocking movement about a horizontal axis extending transversely of the longitudinal axis of the trailer and located to the rear of the vertical axis of said turntable. v

8. In a trailer coupling for a tractor-trailer assembly, a turntable to be rigidly mounted on a tractor, said turntable including a lower fixed .plate and an upper plate secured to said lower plate for angular movement about a vertical axis, trunnions mounted on said upper plate for supporting vhorizontal shaft means with the axis thereof transverse to a trailer and located rearwardly of said vertical axis, shaft means supported by said trunnions, and means supported by said shaft means and adapted to be rigidly secured to a trailer.

9. A trailer coupling for a tractor-trailer assembly, said coupling comprising a turntable to be mounted upon a tractor, said turntable including a lower plate to be rigidly mounted on the tractor, and an upper plate supported for angular movement about a vertical axis with respect to said lower plate, and means on said upper plate for connection to a trailer to transmit the trailer weight to said upper plate at a point rearwardly of the said vertical axis of the turntable.

10. A trailer. coupling as recited in claim 9, wherein said-means mounted on the upper plate includes means supporting said trailer for rocking movement about an axis transverse to the longitudinal center line of the trailer.

11. In a tractor-trailer assembly, a tractor, a trailer, a turntable mounted on said tractor and including upper and lower plates connected for relative angular movement, a bearing plate mounted on said upper turntable plate for rocking movement, a cooperating bearing plate secured to said trailer, a landing gear on said trailer, and locking means controlled by said landing gear for locking said bearing plates against relative angular and longitudinal movements,

12. In a :fifth wheel coupling for a tractortrailer assembly, a. turntable to be mounted on a-,tractor and comprising upper and lower plates connected for relatively angular motion about a vertical axis, and a rocking support for a. trailer secured to sai-d upper plate, the said support having a rocking axis positioned rearwardly of the axis of said turntable.

13. In a tractor-trailer coupling, a turntable to be mounted on a tractor, and a iifth wheel assembly secured to the upper plate of said turntable, said fifth wheel assembly including cooperating bearing plates to be secured respectively to said turntable and to said trailer, means supporting one of said bearing plates on the upper turntable plate for rocking movement about an axis transverse to the longitudinal axis of the trailer, a landing gear for said trailer, and locking means controlled by said landing gear upon movement thereof into retracted position to secure said bearing plates against separation and against relative angular movement.

14. In a tractor-trailer assembly, the invention as recited in claim 13, wherein said locking means includes a pin carried by one of said bearing plates for insertion in an opening in the other bearing plate, spring means tending to project said pin into the opening of said other bearing plate, and means actuated bysaid landing gear vwhen extended into operative position to withdraw said pin from its cooperating opening.

JOHN N. APGAR.

REFERENCES CITED The following references are of record in the le of this patent:

l UNITED STATES PATENTS 

